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222-9+11+12:2*14+14 = ? ( )

Toán Lớp 8: Thực hiện phép tính `a)` $\frac{5xy-4y}{2x^2y^3}$ + $\frac{3xy+4y}{2x^2y^3}$ `b)` $\frac{x+3}{x-2}$ + $\frac{4+x}{2-x}$ `c)` $\frac{x

Tháng Ba 19, 2022 Toán học 2 Comments 0 views

Toán Lớp 8: Thực hiện phép tính
a) $\frac{5xy-4y}{2x^2y^3}$ + $\frac{3xy+4y}{2x^2y^3}$
b) $\frac{x+3}{x-2}$ + $\frac{4+x}{2-x}$
c) $\frac{x+1}{2x+6}$ + $\frac{2x+3}{x^2+3x}$

Comments ( 2 )

  1. hoaiphuong85
    hoaiphuong85
    19 Tháng Ba, 2022 at 10:27 sáng
    Reply
    Giải đáp+Lời giải và giải thích chi tiết:
    a)
    {5xy – 4y}/{2x^2 y^3} + {3xy + 4y}/{2x^2 y^3}
    = {5xy – 4y + 3xy + 4y}/{2x^2 y^3}
    = {8xy}/{2x^2 y^3}
    = {2xy.4}/{2xy.xy^2}
    = 4/{xy^2}
    $\\$
    b)
    {x + 3}/{x -2} + {4 + x}/{2 – x}
    = {x + 3}/{x -2} + {4 + x}/{- (x – 2)}
    = {x + 3}/{x -2} – {4 + x}/{x – 2}
    = {x + 3 – (4 + x)}/{x – 2}
    = {x + 3 – 4 – x}/{x – 2}
    = {- 1}/{x – 2}
    $\\$
    c)
    {x + 1}/{2x + 6} + {2x + 3}/{x^2 + 3x}
    = {x + 1}/{2(x + 3)} + {2x + 3}/{x(x + 3)}
    = {x(x + 1)}/{2x(x + 3)} + {2(2x + 3)}/{2x(x + 3)}
    = {x^2 + x}/{2x(x + 3)} + {4x + 6}/{2x(x + 3)}
    = {x^2 + x + 4x + 6}/{2x(x + 3)}
    = {x^2 + 5x + 6}/{2x(x + 3)}
    = {x^2 + 2x + 3x + 6}/{2x(x + 3)}
    = {(x^2 + 2x) + (3x + 6)}/{2x(x + 3)}
    = {x(x + 2) + 3(x + 2)}/{2x(x + 3)}
    = {(x + 2)(x + 3)}/{2x(x + 3)}
    = {x + 2}/{2x}
    #SunHee

  2. tuyetnhungthu
    tuyetnhungthu
    19 Tháng Ba, 2022 at 10:27 sáng
    Reply
    Giải đáp:
     $a) \dfrac{5xy-4y}{2x²y³}+\dfrac{3xy+4y}{2x²y^3}$
    $= \dfrac{5xy-4y+3xy+4y}{2x²y³}$
    $= \dfrac{8xy}{2x²y³}$
    $= \dfrac{4}{xy²}$
    $b) \dfrac{x+3}{x-2}+\dfrac{4+x}{2-x}$
    $= \dfrac{x+3}{x-2}-\dfrac{4+x}{x-2}$
    $= \dfrac{x+3-4-x}{x-2}$
    $= \dfrac{-1}{x-2}$
    $c) \dfrac{x+1}{2x+6}+\dfrac{2x+3}{x^2+3x}$
    $= \dfrac{x+1}{2.(x+3)}+\dfrac{2x+3}{x.(x+3)}$
    $= \dfrac{(x+1).x}{2.(x+3).x}+\dfrac{(2x+3).2}{x.(x+3).2}$
    $= \dfrac{x²+x+4x+6}{2x.(x+3)}$
    $= \dfrac{x²+5x+6}{2x.(x+3)}$
    $= \dfrac{x²+2x+3x+6}{2x.(x+3)}$
    $= \dfrac{x.(x+2)+3.(x+2)}{2x.(x+3)}$
    $= \dfrac{(x+3).(x+2)}{2x.(x+3)}$
    $= \dfrac{x+2}{2x}$
     

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222-9+11+12:2*14+14 = ? ( )

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